Résumé
Objective To compare the dose distribution between volumetric-modulated arc therapy ( VMAT ) and intensity-modulated radiotherapy ( IMRT ) in patients with brain metastases receiving hippocampus-sparing whole brain radiotherapy. Methods Forty-six patients with brain metastases admitted to our hospital from 2013 to 2016 were recruited in this study. After fusing the CT and MRI images, the hippocampus was delineated on the fusion images. The three-grade hippocampal avoidance regions were created by using a volumetric expansion of 3,5 and 10 mm surrounding the hippocampus. The planning target volume ( PTV) was calculated by subtracting the 5-mm expansion surrounding the hippocampus from the whole brain. The prescription dose was 30 Gy/10 fractions. The 7-field IMRT and single arc VMAT were designed for each case. The dose distribution of PTV,hippocampus and other organs at risk ( OARs) were evaluated in both plans. Results The PTV was statistically compared between VMAT and IMRT:V95:95. 90％ and 94. 97％( P=0. 000 );V90:98. 17％ and 97. 48％( P=0. 000 );CI:0. 825 and 0. 813 ( P=0. 013);HI:0. 277 and 0. 289(P=0. 025).The hippocampal dose was also compared between VMAT and IMRT:the Dmax of hippocampus was 1698. 9 cGy for VMAT and 1784. 9 cGy for IMRT (P=0. 002).TheDmean of hippocampus was 1183. 8 cGy for VMAT and 1112. 7 cGy for IMRT (P=0. 000).No statistical significance was observed between IMRT and VMAT in protecting the OARs except the chiasma opticum ( 3262. 6 cGy and 3529. 3 cGy,P=0. 000).The MU and treatment time of VMAT and IMRT were 651 and 2768( P=0. 000) ,and 188 s and 504 s ( P=0. 000) . Conclusions The dose distribution of PTV in VMAT is significantly better than that in IMRT. VMAT is advantageous in protecting the hippocampus than IMRT. VMAT can significantly shorten treatment time and MU and enhance the equipment utilization. Besides, VMAT can achieve the goal of protecting the hippocampus and meet the prescription dose requirement of PTV.
Résumé
Objective To investigate the clinical efficacy and safety of erlotinib combined with concurrent whole brain radiotherapy (WBRT) in the treatment of multiple brain metastases from lung adenocarcinoma,and to provide objective evidence for improving the prognosis of patients.Methods Eighty-nine patients with brain metastases from epidermal growth factor receptor (EGFR)-mutant lung adenocareinoma who were admitted to our hospital were divided into experimental group (n =45) and control group (n=44) according to the different treatment methods.The experimental group received erlotinib combined with concurrent WBRT.The control group received oral administration of erlotinib alone for 28 d and then received concurrent WBRT.The survival rates were calculated using the Kaplan-Meier method and analyzed using the log-rank test.The other data were analyzed by the chi-square test.Results The objective response rate was significantly higher in the experimental group than in the control group (78％ vs.55％,P=0.000).The median progression-free survival (PFS) time in the experimental group and the control group were 9.1 months (95％ confidence interval [CI]:5.18-12.47) and 5.6 months (95％CI:3.46-9.12),respectively (P=0.078).The median overall survival (OS) time in the experimental group and the controlgroup were 14.3 months (95％CI:9.51-17.82) and 9.7 months (95％CI:4.59-16.74),respectively (P=0.032).The incidence rates of headache and dizziness were significantly higher in the experimental group than in the control group (38％ vs.14％,P=0.029;33％ vs.9％,P=0.020).Conclusions In the treatment of multiple brain metastases from EGFR-mutant lung adenocarcinoma,erlotinib combined with concurrent WBRT is superior to erlotinib alone.The combination therapy increases PFS and OS time of the nervous system in patients.